MODELING AND OPTIMIZATION OF HPGE DETECTOR GC0518 USING MCNP5 CODE

Area of Science:

• Nuclear instrumentation and detector physics.
• Computational physics and Monte Carlo simulations.
• Radiological measurements and calibration.

Background:

• Precise modeling of high purity germanium (HPGe) detectors requires detailed geometric parameters, which are often unavailable.
• Existing detector datasheets may have uncertainties precluding accurate modeling without further corrections.
• Radiographic techniques for geometry determination can be complex or inaccessible.

Purpose of the Study:

• To develop simple, non-radiographic procedures for determining essential HPGe detector geometric parameters.
• To optimize a Monte Carlo N-Particle 5 (MCNP5) model of an HPGe detector using experimental measurements.
• To evaluate the accuracy of the optimized model by comparing calculated and measured full energy peak efficiencies.

Main Methods:

• Utilized MCNP5 code for simulating the HPGe detector (Mirion GC0518).
• Performed experimental measurements using calibration point sources and Marinelli beakers.
• Conducted specific measurements to determine germanium dead layer, crystal holder, inner hole geometry, and crystal edge radii.
• Optimized the MCNP5 model based on experimental data.

Main Results:

• The optimized MCNP5 model accurately represented the HPGe detector's geometry.
• Calculated full energy peak efficiencies showed good agreement with experimental measurements.
• Relative differences were less than 4.5% for point sources and 5.4% for Marinelli beakers.

Conclusions:

• The proposed simple procedures effectively determine HPGe detector geometry without radiography.
• The optimized MCNP5 model provides a reliable tool for precise efficiency calculations.
• This method enhances the accuracy of HPGe detector characterization for various applications.